Isolation and characterization of Vibrio alginolyticus strain HAT3 causing skin ulceration disease in cultured sea cucumber Holothuria atra (Jaeger, 1833)

Abstract

Skin ulceration disease is widespread among aquacultured holothuroids. Herein, we report on the skin ulceration disease of juvenile Holothuria atra reared in the Aquaculture Laboratory of the National Institute of Oceanography and Fisheries in Hurghada, Red Sea, Egypt. The disease caused the death of the animals within 3 days, and the signs included depigmentation of the epidermis, visceral ejection, and autolysis of the body. The dominant bacterial isolate obtained from the individuals with lesions on the skin was labelled as HAT3, and was selected for characterization and disease induction assay. Based on the morphological and biochemical characteristics, and 16s rDNA gene sequence analysis, the isolate HAT3 was identified as a strain of Vibrio alginolyticus and designated as V. alginolyticus strain HAT3. The 16s rDNA gene sequence was deposited in the GenBank under the accession number MW546612. The experimental infection of healthy H. atra with V. alginolyticus strain HAT3 induced the disease with the same signs as the naturally infected H. atra. Our results revealed that V. alginolyticus strain HAT3 was the causative pathogen of skin ulceration disease in reared H. atra.